Mitsubishi Lancer Evolution IX. Manual - part 411

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-119

STEP 4. Perform voltage measurement at B-18 
No. 3 injector connector.

• Disconnect connector, and measure at harness 

side.

• Ignition switch: "ON" 

• Voltage between terminal No. 1 and earth.

OK: System voltage

Q: Is the check result normal? 

YES : 

Go to Step 8 .

NO : 

Go to Step 5 .

STEP 5. Connector check: B-12X engine control 
relay connector

Q: Is the check result normal? 

YES : 

Go to Step 6 .

NO : 

Repair or replace the connector.

STEP 6. Check injector resistor itself.

• Check injector resistor itself (Refer to 

P.13A-407

).

Q: Is the check result normal? 

YES : 

Go to Step 7 .

NO : 

Replace the injector resistor.

STEP 7. Check harness between B-119 (terminal 
No. 5) injector resistor connector and B-18 
(terminal No. 1) No. 3 injector connector.

• Check power supply line for open/short circuit.

AK305012

1

2

Connector : B-18

Harness side connector

B-18(B)

AE

AK305003

2

1

3

4

AB

Connector : B-12X

B-12X

Harness side 
connector

Relay box’s
triangle marks

AK305016

1

2

3

4

5

6

AB

Harness side 
connector

B-119(B)

B-119(B)

Connector : B-119

<L.H.drive vehicles>

<R.H.drive vehicles>

AK305012

1

2

Connector : B-18

Harness side connector

B-18(B)

AE

AK305003

2

1

3

4

AB

Connector : B-12X

B-12X

Harness side 
connector

Relay box’s
triangle marks

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-120

Q: Is the check result normal? 

YES : 

Check intermediate connector C-105, and 

repair if necessary. If intermediate 
connector are normal, check and repair 
harness between B-119 (terminal No. 3) 
injector resistor connector and B-12X 
(terminal No. 4) engine control relay 
connector.

• Check power supply line for 

open/short circuit.

NO : 

Repair the damaged harness wire.

STEP 8. Check harness between B-119 (terminal 
No. 5) injector resistor connector and B-18 
(terminal No. 1) No. 3 injector connector.

• Check power supply line for damage.

Q: Is the check result normal? 

YES : 

Go to Step 9 .

NO : 

Repair the damaged harness wire.

STEP 9. Check harness between B-119 (terminal 
No. 3) injector resistor connector and B-12X 
(terminal No. 4) engine control relay connector.

NOTE: Before checking harness, check intermediate 
connector C-105, and repair if necessary.

• Check power supply line for damage.

Q: Is the check result normal? 

YES : 

Go to Step 10 .

NO : 

Repair the damaged harness wire.

AK305016

1

2

3

4

5

6

AB

Harness side 
connector

B-119(B)

B-119(B)

Connector : B-119

<L.H.drive vehicles>

<R.H.drive vehicles>

AK305012

1

2

Connector : B-18

Harness side connector

B-18(B)

AE

AK305016

1

2

3

4

5

6

AB

Harness side 
connector

B-119(B)

B-119(B)

Connector : B-119

<L.H.drive vehicles>

<R.H.drive vehicles>

AK305003

2

1

3

4

AB

Connector : B-12X

B-12X

Harness side 
connector

Relay box’s
triangle marks

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-121

STEP 10. Connector check: C-121 engine-ECU 
connector

Q: Is the check result normal? 

YES : 

Go to Step 11 .

NO : 

Repair or replace the connector.

STEP 11. Check harness between B-18 (terminal 
No. 2) No. 3 injector connector and C-121 
(terminal No. 24) engine-ECU connector.

• Check output line for open/short circuit and dam-

age.

Q: Is the check result normal? 

YES : 

Go to Step 12 .

NO : 

Repair the damaged harness wire.

AK501995

2

3

4

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

30

21

22

23

24

25

26

27

28

29

31

32

33

34

35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

AK305012

1

2

Connector : B-18

Harness side connector

B-18(B)

AE

AK501995

2

3

4

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

30

21

22

23

24

25

26

27

28

29

31

32

33

34

35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>

TROUBLESHOOTING

MULTIPORT FUEL INJECTION (MPI)

13A-122

STEP 12. Perform signal wave pattern 
measurement at C-121 engine-ECU connector 
(Using an oscilloscope).

• Engine: Idling

• Transmission: Neutral

• Voltage between terminal No. 24 and earth.

OK: Waveform should be display on Inspec-
tion procedure using an oscilloscope (Refer 
to 

P.13A-385

).

Q: Is the check result normal? 

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Use 

Troubleshooting/Inspection Service Points 

P.00-5

).

NO : 

Replace the engine-ECU.

AK501995

2

3

4

5

6

7

8

9

11

12

13

14

15

16

17

18

19

20

30

21

22

23

24

25

26

27

28

29

31

32

33

34

35

1

10

AB

Connector: C-121

C-121 (GR)

C-121 (GR)

Harness side connector

<L. H. drive vehicles>

<R. H. drive vehicles>